Variable-throw crank.



No. 772,494. PATENTBD OGT.18,-1904.

' M. BARR.

VARIABLE THROW 01mm.

APPLICATION-FILED JUNE 29, 1901.

1 sums-sunn- 1.-

NO MODEL] fluke/ZZZ?" ufllorlwy Waves PATENTED 00w. 13, 1904.

BARR. VARIABLE THROW CRANK.

APPLICATION IILBD JUNE 29, .1901.

7 SHEETS-SHEET 2.

N0 MODEL.

No. 772,494. PATENTED oer. 1a, 1904. M. BARR. VARIABLE THROW CRANK.

APPLIOATIOH FILED JUNE 29, 1901.

N0 MODEL. 7 SHEETS-SHEET 3.

v e/2'07" #WW v Jflarrwy m /72,494. PATENTED 001'. 18, 1904.

M. mm.

VARIABLE THROW CRANK.

APPLICATION FILED JUNE 29, 1901.

N0 MODEL. 7 SHEETg-SHHET 4.

dam-hey PATENTED OCT. 18, 1904.

nuns-sum a.

M. RRL VARIABLE THROW CRANK.

APPLICATION FILED JUNE 29, 1901.

so MODEL.

[law/M07 WWW W0 Jtlmrrwy.

lnesses No. 772,494. PATENTEDIOOT. 1s, 1904.

M. BARR."

VARIABLE THROW CRANK.

, APPLICATION FILED JUNE 29, 1901,

no MODEL. 7 SHEETS-SHEET 7] msw I, v [ru e/Mar Patented October 18, 1904'.

- 1 UN TED STATES-PATENT OFFICE.

MARK BARR, or knNsme'roN, ENGLAND, ASSIGNOR To THE LINOTYPE COMPANY, LIMITED, LONDON, ENGLAND.

' VARIABLE-THROW CRANK.

SPECIFICATION forming part of Letters Patent No. 772,494, dated October 18, 1904.

' Application filed June 29,1901.

To all whom it may concern:

Be it known that I, MARK BARR, of 25. Kensington Court Gardens, Kensington, in the county of Middlesex, England, have invented certain new and useful Improvements in Variable-Throw Cranks; and I do hereby declare the following to be a full, clear, and exact ping the said machines, the construction of' the said devices being such as to enable these adjustments to be very readily and veryaccurately effected.

As an example of one useful application of the improved crank it is hereinafter described and in the accompanying drawings is repre sented as applied to a machine for grinding the cutting-tools of engraving-machines, this grinding-machine being also provided with means whereby the abrading-surface can be periodically dressed. It is owing to the presence; in the said same machine of the grinding and dressing devices that the variable-crank mechanism becomes necessary, the reason being that during the grinding operation the relative motion between the tool being ground and the abrading-surface requires to be such that the said tool and surface do not completely traverse each other, whereas during the dressing operation the diamond or otherdresser must completely traverse the abrading-surface, or vice versa, so as to insure that the said surface shall be rendered uniform. i

In the drawings, Figure 1 is a plan of the 7 said grinding-machine with the improved crank device applied thereto; Fig. 2, a front elevation corresponding therewith; Fig. 3, a side elevation of Figs. 1 and 2 from the left hand; Fig. 4, aside elevation of Figs. 1 and 2 from the right hand; Fig. 5, a detail vertical section of the improved crank-gear, taken Serial No. 66,620. (No model.)

on the line 5 5 of Fig. 1; Fig. 6, a plan of vFig. 5; Fig.7, a detail vertical section on the line 7 7 of Fig.1; Fig. 8, a plan of Fig.

7; Fig. 9, a perspective view of the wedgeshaped sector and part. of its rod, and Fig. 10, a detail plan. of parts of Figs. 5 and 6.

The machine represented in the drawings is constructed as follows: A suitable base A carries a bearing B, in which turns a tube D, supporting the improved grinder or abrader 1. This grinder or abrader 1 is annular and has an annular grinding-face 2. The grinder 1 is held fast to a tube D, turning in the bearings B, D being the driving-pulley of the tube D. The bearing B is fast on a slide adapted to work in stationary guides 6 6 on the base A, a ball-race .7 being interposed between each side of the slide 5 and the re spective guide 6.

8 is a crank-pin standing up from a disk 9, mounted to turn about a vertical axis in a bearing 10 in a part of the frame A under the slide 5. The crank-pin 8 is connected to the disk 9 in a particular way described farther on; but it is fast thereto and eccentric therewithfor any given working position.

11. is a slot in the slide 5 at right angles with its reciprocating motion.

12 is the driving-pulleyfor rotating the 1 disk 9 to reciprocate the slide 5, and 13 is its shaft, turning in bearings 14 14 on the base A.

15 is a worm on the shaft 13 gearing with a worm-wheel .16 on a shaft 17, carrying a worm 18, gearing with a worm-gear 19 on the.

periphery of the disk 9. Thus the rotation of the driving-pulley 12 reciprocates the grinding-face 2 past either the tool end W or the diamond dresser F,whichever may be in workon the tool or of a notch in it. In practice, however, the motion of the grinding-face during the grinding operation must be less than the width of that face. The diamond dresser F occupies a similar position to the other side of the grinding-face 2; but the latter must be moved past it for a distance longer than the width of the face 2 to insure the latter being faced over the whole of it. Consequently the eccentricity of the crank-pin 8 to the disk 9 must be adjustable to satisfy the respective requirements of grinding the tool and d ressing the grinding-face 2. This adjustability, according to the present invention, is effected by the following means.

is a concentric sink in the disk 9, and 21 21 are a pair of segments undercut along their straight edges and held down in 20 by a screw 22, thereby establishing a diametrical groove 23.

24 is a block capable of sliding along this slot in either direction, and it is to this block 24 that the crank-pin 8 is made fast. The block 24 is shorter than the groove 23 by a distance equal to the maximum variation in the eccentricity above mentioned.

25 is a spindle having a milled head 26 and a screw-thread 27 upon it engaging in a bridgepiece 28, extending over the slide 5 and secured to the base A.

29 is a second screw-thread on the spindle 25 lower down it than the thread 27 and of double the pitch of the latter.

30 is a ring capable of a reciprocating vertical motion in a guide 31, fast to and depending from the bridge-piece 28, under the action of the screw-thread 29, with which it is screwthreaded to engage, and 32 is a spline fast to the guide 31 and engaging on a corresponding vertical groove in the side of the ring 30.

33 is an external cone on the bottom end of the spindle 25, and 34 is a cone on the inside face of the ring 30, around the bottom thereof, the two cones being opposite to and parallel with each other. The top of the pin 8 is likewise coned to the same angle as the two cones just described and of a proper diameter to fit with a working fit up to either cone 33 or 34, there being a slight clearance between them, as indicated in Fig. 5. To prevent friction between either cone 33 or 34 and the top of the pin 8, the latter carries a thimble 35. Fig. 5 shows the spindle 25 as far down through the bridge 28 as it will go and the pin 8 over to the right as far as it is required to be, that position corresponding to the dressing action of the dresser F upon the grinding-face 2 and giving the maximum travel to the bearing B. If now the spindle 25 is turned up through the bridge 28, the cone 33 will be raised and the cone 34 lowered, both at the same rate, for the reason that they move in opposite directions, and the pitch of the screw-thread 27 is half that of the screw-thread 29, the depression of the cone 34 pushing the crank-pin 8 before it along the slot into the position shown by the dotted lines in Fig. 1, that position corresponding with the grinding action of the face 2 upon the tool and giving the minimum travel to the bearing B. The consequent elevation of the cone 33 takes the latter out of the way of the crank-pin 8 at the rate necessary to allow of the free lateral adjustment of the said crank-pin.

36 is a post fast on the base A. 37 is an arm pivoted to swing about a vertical axis on the top of the post 36, the pivot being of considerable strength.

F is the diamond dresser fast in the end of the carrier 38, which is passed through a socket of the same cross-section in the arm 37.

39 is a locking-screw. working downward through the arm 37 to lock the diamond dresser F either in or out of work, which it does by having its coned end 40 entered into one of two conical holes 41, properly positioned in the quadrant 42, which projects bracketwise from the top of the post 36 immediately under the said arm 37 to support the holes 41 41 in the required positions. The carrier 38 is in cross-section circular, modified by a fiat 33 on one side. It slides in a socket of the same cross-section in the arm 37. This socket is closed by the end plate 44, with which is incorporated a screw-threaded nipple 45, the latter becoming thereby a part of the arm 37.

46 is an internally-screw-threaded cap held. to the front end of the carrier 38 by a screw 47, about which it can turn freely to engage with the nipple 45 for the purpose of adjusting the distance which the dresser F projects beyond the arm 37.

It is the slide S that carries the wire \V the end of which is to be ground into the tool and the stop-block T that limits the motion of the slide S up to the grinding-face 2; but before the working position of the block T can be determined it and the slide S must be temporarily held together as if they were one piece, for which purpose the stop-block T has a transverse segmental cavity 46 in its bottom face, in which can engage a wedge-shaped sector 49, fast on the inner end of a rod 50, turning in bearings 51 51, depending from the slide S and projecting to the front through the base A, where it carries a handle 52 within reach of the operator. The taper of the sector 49 is on its front face, its rear face being at right angles with its axis, and the contour of the cavity 46 corresponds with that of the wedge.

53 53 are a pair of collars one on each side of one of the bearings 51 and both fast to the rod to prevent the latter moving lengthwise in its bearings.

54 is a removable cover sliding in the base A to give access to the meeting faces of the slide S and the stop-block T. The slide S and the stop-block 'I are temporarily locked together by turning the sector 49 up into the cavity 46. i

I claim 1, In a variable-throw crank the combination with a crank-disk and a crank-pin radially adjustable therein, of an external cone coaxial with the crank-disk in operative contact with the inner side of the crank-pin, an internal 'cone concentric with the external cone andv in operative contact with the outer side of the crank-pin, the two cones being adj ustable in the direction of their common axis,

and means in operative connection with the two cones for simultaneously and to the same extent advancing and retracting the respective cones in the direction of their common axis.

--2. In a variablethr0w crank the combination with a crank-disk and a crank-pin radially adjustable therein, of a rotatable spindleing the ring from rotating, intermeshing screw-threads onthe spindle and ring, and intermeshing screw-threads on the spindle and bridge-piece the pitch of the former screw- I threads being twice that of the latter ones.

3. In a variable-throw crank the combination with a crank-disk and a crank-pin radially adjustable therein, of a cone on the crankpin, a conical thimble loose on this cone, a rotatable spindle coaxial with the crank-disk, an external cone on the spindle in contact with the inner side of the thimble, a ring concentric with the spindle, an internal cone on the ring, in contact with the outer side of the In witness whereof I have hereuntoset my I hand in the presence of two witnesses.

MARK BARR.

Witnesses:

CHAS. S. WOODROFFE, WALTER J. SKERTEN. 

